1. Field of the Invention
The present invention relates to a manufacturing method of a tubular body made of a fiber reinforced resin, and a tubular body manufactured by the manufacturing method.
2. Description of the Related Art
In recent years, it has been desirable to develop a golf club shaft (hereinafter, referred to as a shaft) capable of increasing a flight distance by a small force with an increase in the number of elderly and female golf players with weak power. In particular, a reduction in a weight of the shaft has been supposed to be one of effective means for solving the problem, and various programs have been made.
As the programs, a change from steel to FRP (fiber reinforced plastic) can be taken. As a method of manufacturing the FRP tubular body, a sheet winding process and a filament winding process are well known. The sheet winding process winds a prepreg sheet around a mandrel (cored bar), further winds a wrapping tape, and thermally cures the prepreg sheet. The winding of the wrapping tape prevents the prepreg sheet from slipping from the mandrel in a heating step (curing step). The heating reduces the viscosity of a matrix resin of the prepreg sheet. However, the winding of the wrapping tape suppresses the deformation of a formed body.
For the conditions of the curing step, Paragraph [0032] of Japanese Patent Application Laid-Open No. 2004-224979 discloses a curing temperature of 80° C. or higher and 150° C. or lower, and a curing time of 1 hour or longer and 12 hours or shorter. FIG. 3 of Japanese Patent Application Laid-Open No. 2004-224979 describes temperature conditions in examples. Japanese Patent Application Laid-Open No. 2004-224979 uses several types of thermosetting epoxy resins as a matrix resin, and a polypropylene tape as a wrapping tape.
Japanese Patent Application Laid-Open No. 2006-124555 discloses a composition containing an epoxy resin, a curing agent and fullerenes as an epoxy resin composition for a fiber reinforced composite material. The gazette discloses conditions 130° C. and about 90 minutes as the conditions of the curing step.